Corm Growth Research Articles

Impact of Silicon Application on Corms and Cormels Growth in Gladiolus (Gladiolus grandiflorus Hort.) cv. ‘White Prosperity’

The objective of present study was to assess the impact of different doses and method of silicon application on growth of underground corms and cormels in gladiolus (Gladiolus grandiflorus Hort.) cv. White Prosperity. The experiment was conductedat Punjab Agricultural University, Ludhiana, Punjab, India during 2021-22. The experiment was designed in split plot randomized block design with three replications. It encompassed five basal doses of silicon (0, 25, 50, 75 and 100 kgha-1 as SiO2) along with four foliar sprays at 3rd and 6th leaf stage (water spray, 1%, 2% and 3% as SiO2). The results showed that corm and cormel production was enhanced with linear increase in silicon dose as basal as well as foliar application with maximum at 100 kgha-1(1.40 and 28.74) and 3% (1.42 and 29.42). However, combined application recorded significantly maximum number of corms and cormels per plant (1.80 and 37.12) with 75 kgha-1+ 3% and 100 kgha-1+ 3%. Combined application of silicon @75 kgha-1as basal and 2% as foliar produced maximum corm weight (38.46 g), whereas cormels weight per plant (28.47 g) was observed maximum with 100 kgha-1basal application along with 3% foliar spray. Basal application of silicon dioxide gave more values for corm traits as compared to foliar application. Hence, it was concluded that silicon application at 100 kgha-1as basal along with 3% foliar spray at 3rd and 6th leaf stage could be recommended to improve underground corm and cormel production in gladiolus.

Transcriptome-based identification and validation of reference genes for corm growth stages, different tissues, and drought stress in Taro (Colocasia esculenta)

Taro is a widely utilized starch resource plant. It is essential to quantify the expression levels of functional genes associated with taro growth using real-time quantitative polymerase chain reaction (RT-qPCR). However, to obtain reliable RT-qPCR results, appropriate reference genes (RGs) are required for data normalization. In this study, we screened seven novel candidate RGs using transcriptome datasets from taro, encompassing data from growth corms and various tissues. The expression stability of these seven new RGs, along with the commonly used RGs Actin, EF1-α, and β-tubulin, was assessed using Delta Ct, BestKeeper, geNorm, and NormFinder algorithms. Furthermore, we conducted a comprehensive analysis using the RefFinder program and validated the results using the target gene, CeAGPL1. The findings revealed that ACY-1 and PIA2 were the optimal multiple RGs for normalization during corm growth, while COX10 and Armc8 were suitable for samples including various types of tissues. Furthermore, we found three RGs, Armc8, COX10 and CCX4L, were the optimal RGs for drought stress. This study assessed the suitability of RGs in taro for the first time. The identified RGs provide valuable resources for studying corm growth, diverse tissues, and drought stress. This study contributes to the advancement of our understanding of the underlying mechanisms that govern the growth of taro.

Understanding the Saffron Corm Development-Insights into Histological and Metabolic Aspects.

The reproduction of Crocus sativus L., a sterile triploid plant, is carried out exclusively through corms, whose size determines the saffron yield. The development of daughter corms (DC) is supported by photoassimilates supplied by the leaves as well as by the mother corms (MC). While biomass partitioning during DC development is well studied, growth dynamics in terms of cell number and size, the involved meristems, as well as carbohydrate partition and allocation, are not yet fully understood. We conducted a comprehensive study into saffron corm growth dynamics at the macroscopic and microscopic levels. Variations in carbohydrate content and enzymatic activities related to sucrose metabolism in sources and sinks were measured. Two key meristems were identified. One is involved in vascular connections between DC and MC. The other is a thickening meristem responsible for DC enlargement. This research explains how the previously described phases of corm growth correlate with variations in cell division, enlargement dynamics, and carbohydrate partitioning among organs. Results also elucidated that the end of DC growth relates to a significant drop in MC root biomass, limiting the water supply for the DC growth, and establishing the onset of leaf wilting. The lack of starch accumulation in aged leaf cells is noteworthy, as is the accumulation of lipids. We hypothesize a signaling role of sugars in DC growth initiation, stop, and leaf aging. Finally, we established a predominant role of sucrose synthase as a sucrolytic enzyme in the maintenance of the high flux of carbon for starch synthesis in DC. Together, the obtained results pave the way for the definition of strategies leading to better control of saffron corm development.

Drought Stress Inhibits Starch Accumulation in Taro (Colocasia esculenta L. Schott).

Colocasia esculenta L. Schott is a main traditional root crop in China, serving as an important vegetable and staple food. Drought stress plays vital role on the growth and development of taro corm. Two different varieties of taro in Jiangsu were selected: Xiangsha taro and Longxiang taro. The accumulation characteristics, morphological structure, and physicochemical properties of taro corm starch were studied by microscopic observation, particle size analysis, and X-ray diffractometer (XRD) analysis. Transcriptome analyses were used to identify the related genes of taro corm under drought stress. During the growth of taro, the number of amyloplasts showed an obvious increasing trend and shifted from being dispersed throughout the cells to being gathered on one side of the cells, and morphological observations showed that smaller granular distribution gradually changed to a larger lumpy distribution. The particle size of Longxiang taro is smaller than that of Xiangsha taro. Under drought stress conditions, the occurrence of starch grains and corm size were inhibited in Xiangsha taro. Transcriptome sequencing of drought-stressed taro corms showed that the enzymes related to starch synthesis were differentially expressed. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of drought-stressed taro corms showed that drought affected hormone signal transduction, material metabolism, drought stress tolerance, plant growth and development, and stress resistance, which triggered the plant drought adaptive response. Drought stress inhibits starch accumulation in taro.

ASSESSMENT OF BIOLOGICAL DAMAGE AND TOXIC POTENCY OF COLCHICINE IN GLADIOLUS (GLADIOLUS GRANDIFLORUS) PLANTS

Colchicine is one of the important aqueous solutions that has been used to induce mutation or ploidy in many plant species long ago. However, its proper concentrations plays a vital role, increased or inappropriate concentrations may cause mortality, stunted growth, morphological deformation, etc. in plant species. Thus, this study was conducted to evaluate the different colchicine concentrations on the growth and development of gladiolus corms. Gladiolus corms were treated with 0.2%, 0.4%, and 0.6% concentrations for 24 hours. Colchicine toxicity was evaluated during the early growth stage showed a higher concentration of 0.6% significantly reduced corm survival (47%) and caused a 51.9% survival reduction over control. In terms of growth parameters, all concentrations of colchicine reduced plant height with a number of leaves along with inducing different forms of morphological abnormalities and chlorophyll mutants. To optimize the dose for successful ploidy induction, LD30 and LD50 on mortality rate through an analysis were calculated to be 0.31% and 0.57% whereas GR50 based on plant height and the number of leaves reduction was found to be 0.17% and 0.34%. Hence, the results from this study could be used in the future for further breeding programs by reducing the genotoxicity of colchicine on gladiolus.

ASSESSMENT OF BACILLUS STRAINS ON CORN GROWTH AND YIELD UNDER FIELD CONDITION

Plant growth promoting rhizobacteria enhance crop growth and yield by plant nutrient solubilization and mineralization, symbiotic and associative nitrogen fixation, hormone and water soluble vitamin productions. Ten strains of the genus Bacillus, characterized by their properties related to the promotion of plant growth, were evaluated to determine their effects on corm growth, development and yield under field condition. The experimental design was completely randomized plot with four repetitions. Corn seeds were treated with 10 different Bacillus strains before planting. Compared with the control, Bacillus subtilis and two unidentified Bacillus strains SZF04 and SZF07 highly increased plant height, stem diameter, ear length, seed number/ear, 1000 seed weight and seed yield/plant. Seed treatment with Bacillus strains could be an alternative option to increase corn yield without extra chemical fertilizers inputs.

Clean application of pistachio residues-based vermicompost with γ-aminobutyric acid can alleviate the negative effects of high soil pH on P uptake in saffron (Crocus sativus L.)

In semiarid areas dominated by calcareous soils, a large portion of available P may be deformed into insoluble structures due to the chemical activity of carbonate compounds. This phenomenon, known as P deficiency stress, is considered one of the most important limiting factors for saffron (Crocus sativus L.) production. To avoid P limitation, the application of clean and practical techniques has been emphasized to improve saffron adaptability grown in P-deficient calcareous soils. Hence, field experiments were conducted based on a factorial randomized complete block design with three replicates during 2017–2018 and 2018–2019 (farm 1) and repeated during 2018–2019 and 2019–2020 growing seasons (farm 2). Four levels of γ-aminobutyric acid (GABA) (0, 0.5, 1, and 2 mg L−1) and soil amendments (control, pistachio residues-based vermicompost (VP: 10 t ha−1; 50% in each growing season), sulfur (S: 100 kg ha−1; 50% in each growing season), and VP +S) were considered as experimental factors. From the results, application of VP, S, and VP+S decreased soil pH and increased Olsen-P, microbial biomass, and microbial respiration. Furthermore, the increase was observed for flower number, proline content and corm growth. Following GABA foliar application, flower number, proline content and P availability improved. Compared to control treatment, P concentration in large-sized daughter corms increased by 23.6, 16.8%, and 30.8%, following VP, S, and VP +S, respectively. Among the treatments, the highest P acquisition efficiency (39.2%) were recorded by applying VP +S along with 2 mg L−1. Overall, the results recommend the co-application of VP with GABA foliar spray to improve saffron production grown in calcareous soils of semiarid regions.

Shoot Emergence, Leaf Expansion, and Corm Growth in Amorphophallus muelleri Blume Treated with Hydropriming and Shading

A bulbil, as planting material, is difficult to stimulate to grow in a dormant state. This study examines the hydropriming effect on shoot emergence and the shading treatments on leaf and cormel growth during the vegetative stage. The priming was carried out by soaking the bulbils in distilled water for 0, 3, 6, 12, and 24 hours and the shading treatments at 0, 40, and 80 percent. The results show that the imbibition occurred immediately during the first 3 hours and continued to increase up to 24 hours. The bulbil re-drying process reached the pre-treatment water content in less than three days. Significantly the earlier emergence was observed in the plants exposed to the 80% shading. The petiole sheath breakup was not affected by the hydropriming and shading. The konjac planted in the shading treatment produced more sprouts, longer but slender petioles, larger but thinner leaves, and larger cormel size. The differences in fresh and dry weight were more related to tuber moisture content than the direct effect of the shading treatment. The SPAD value of konjac leaves immediately increased within a few days after the application of the NPK fertilizer and consistently lasted for four weeks.

Measuring the length of the juvenile phase and corm growth in the Chilean endemic geophyte Conanthera bifolia Ruiz et Pavon

The geophyte Conanthera bifolia is endemic to Chile and belongs to the family Tecophilaeaceae. When in flower, the plant produces an inflorescence with blue florets. Conanthera plants arise from underground structures called corms; these have been reported to have been consumed as food in the past. These plants also have ornamental potential as garden or pot plants. The new corm starts growing on top of the mother corm by the end of summer; blooming occurs in the spring, and the plant goes dormant after fruit set. The corm flowering size and juvenile phase length in C. bifolia are unknown. The study objective was to determine the weight of the corm that is necessary for flowering and the number of seasons required to reach that weight. Corms were collected from the wild, separated into 10 weight categories from 0.2 to 5 g, and planted in trays in an unheated greenhouse in Talca, Chile. Corms weighing more than 1 g were able to flower, and the greatest flowering (48 to 70%) was found in corms weighing 3.5 to 5 g. The plant propagation coefficient decreased as the initial corm weight increased. The number of seasons to reach flowering size was estimated to be 8 years, placing this species in the group of geophytes with slow growth.

Responses to defoliation and fertiliser, corm development and chemical control of onion grass (Romulea rosea) in the Mediterranean environment of southern Australia

AbstractBackgroundOnion grass (Romulea rosea) is a common weed that infests native and improved pastures in the Mediterranean environments of southern Australia. It is a very challenging weed to control due to its distinctive growth and survival mechanisms involving corms.MethodsThree glasshouse experiments were conducted in Australia to investigate the response of onion grass to defoliation and fertiliser application, the development and growth of onion grass corms and the chemical control of the weed in winter and spring.ResultsDefoliating consistently to 1 cm above ground reduced corm weight by 84% compared with the control. Medium or high fertiliser application did not increase herbage mass of onion grass compared with the nonfertilised treatment. The corm weight of onion grass declined from Weeks 1 to 8 after emergence, remained at 53–60 mg dry matter (DM) corm−1 from Weeks 8 to 19 and then declined on average to 37 mg DM corm−1 up to Week 26 after emergence. New corms started to develop at Week 6 after emergence. A small proportion of the onion grass plants (7.5%) developed multiple new corms (3–6 corms) from a single old corm. The most effective herbicide control was a winter application of metsulfuron methyl or imazamox as an alternative product to protect clover.ConclusionsThis study has identified the growth and development patterns of onion grass corms, how the plant responded to defoliation and fertiliser application and effective chemical control of this weed. These findings have significant practical implications for the improvement of onion grass‐infested pastures.

INFLUENCE OF COW MANURE IN PLANTING MEDIA AGAINST THE GROWTH OF BANANA CORM OF BANANA KEPOK (Musa paradisiaca L.)

This study aims to obtain the composition of soil and cow dung that provides the best growth for kepok banana seedlings using banana corm.. This research was conducted in Sijunjung Regency. Efforts to provide banana seeds are carried out by utilizing banana corm which will produce 3 and 4 tillers per tuber and the production time is much faster than seeds from tillers. To get the best banana corm growth, a study was conducted using a mixed planting medium of soil and cow manure with five comparisons. The treatments were: A. Soil with cow manure 1:1 ratio, B. Soil with cow manure 2:1 ratio, C. Soil with cow manure 3:1 ratio, D. Soil with cow manure 4:1 ratio, E .Soil only. The treatment was repeated 5 times. The design used was a randomized block design and continued with DNMRT (Duncan New Multiple Range Test). Parameters observed were when shoots appeared, percentage of growth, shoot height, stem diameter, number of leaves, leaf length, root length and number of roots. The results showed that the best planting medium for planting banana kepok from corm was a medium consisting of soil and cow manure with a ratio of 1:1. This treatment gives the best results for all parameters.

Effects Of Different Planting Times and Corm Sizes on Plant Growth, Development, and Flower Production Of Gladiolus (Gladiolus grandiflorus) under Sanliurfa Conditions

The aim of the present study was to determine the effect of different planting times and corm sizes on plant growth, development, and flower yield in Gladiolus. The Red Beauty variety was used as the study material. In the study, two corm sizes (10–12 and 12–14 cm) and five different planting times (April 1, April 15, May 1, May 15, and June 1) were used. The sprouting time (day), flowering time (day), plant height (cm), number of leaves (number/plant), length of the flower stem (cm), length of the spike (cm), number of florets (number/spike), thickness of the flower stem (mm), diameter of the new corm (cm), circumference of the new corm (cm), number of new corms (number/plant), weight of new corm (g/plant), number of cormels (number/plant) and weight (g/plant) and corm yield (g/plot) were determined. We determined that the planting times indicated were suitable for cultivation under Sanliurfa conditions in terms of yield and quality. The best Gladiolus cultivation times in Sanliurfa varied, but the best results were obtained from large corms (12–14 cm). As the temperature increased, corm growth times increased, and plant height, number of leaves, new corm weight, and cormel number and weight decreased. The maximum flowering time and parcel yield were obtained from the fifth planting (June 1), the longest spikes, maximum number of florets, maximum number of cormels and greatest cormel weight, and greatest plant height were determined from the first and second planting times. There was no significant difference between planting times for the other investigated parameters. The large corms (12–14 cm) were observed to be better than small corms (10–12 cm) for increases in most of the parameters investigated.

Cultivation of Saffron (Crocus sativusL.) in cold climates

Saffron, an autumn crocus that produces a highly valuable spice, is grown mainly in Mediterranean climates. Nevertheless, saffron farms have been established recently in the province of Quebec. This led us to test cultivation practices that could influence plant phenology, saffron yield, and corm growth, including planting depth, planting period, and the application of fertilizers, mycorrhizal fungi, and biostimulants at planting. Soil temperature was monitored at the different planting depths throughout the year. Floral initiation was also monitored during spring and summer. Shoot emergence was delayed and final emergence reduced as planting depth increased; however, more shoots were produced by shallow-planted corms, which could lead to the production of corms too small to flower. The best time for planting saffron corm is between the end of July and the third week of August. Mineral fertilization hastened leaf emergence and improved corm production and their nutrient content. Neither the addition of mycorrhizal fungi or of biostimulants had any significant impact on saffron growth or flowering. Floral induction likely took place in July as flower bud appeared in early August. In most years, flower and saffron production was low in this location. It appears that soil temperature did not remain high for long enough during the summer to promote floral induction and autumn temperatures decreased too fast, limiting shoot and flower emergence most years. However, these climatic conditions did not affect corm production; corms could thus be sold to secure revenues for producers.

Induction of polyploidy in saffron (Crocus sativus L.) using colchicine

ABSTRACT Saffron (Crocus sativus L.) is triploid (2 n = 3x = 24, x = 8), which limits its improvement through crop breeding programs. This study was initiated to induce hexaploidy with the intent of restoring sexual stability in saffron. Corms were treated with colchicine concentrations of 0.0%, 0.025%, 0.05%, and 0.1% for 3-h, 6-h, and 9-h. A total of 16 in-vitro shoots showed signs of polyploidization. These colchiploid shoots showed slow but robust growth and produced large-sized cormlets (6.0 g) compared to the control (2.8 g). Leaf epidermal cell morphology, stomatal size and density showed evidence of polyploidization. Hexaploidy (2 n = 6x = 48) was confirmed by root-tip cytology. The hexaploid corms germinated but could not establish in the field. We were able to develop a protocol for in-vitro induction of hexaploidy in C. sativus, but the subsequent growth of hexaploid corms in the field remains a major challenge in restoring the sexual stability in saffron.

Do corm seeding rate and planting depth influence growth indicators of saffron (Crocus sativus L.)?

Saffron, the primary in the market now, is a food spice by far the world’s most expensive. In order to study the effects of different corm seeding rates and sowing depth on physiological indices of saffron, an experiment was conducted as a factorial layout based on randomized complete block design with three replications at the research farm of the Ferdowsi University of Mashhad during 2015–2017 years. The experimental treatments were all combinations of different corms seeding rates in four levels (7, 8, 9, and 10 Mg ha−1) and sowing depth in three levels (10, 15, and 20 cm). The studied traits were the dry weight of mother and daughter corms, cumulative dry matter, and some growth indices such as leaf area index (LAI), crop growth rates (CGR), relative growth rate (RGR), and Leaf Area Ratio (LAR). The results showed 8 Mg ha−1 corm seeding rate and 10 cm sowing depth increased total crop dry weight, CGR, and RGR in saffron. Based on obtained results at the beginning of the vegetative growth period, CGR declined for a short time. So that by continuing the vegetative growth, the plant reached on growth compensation point, and then CGR increased. From 180 days after the sowing date and in the late stages of vegetative growth, the growth rates trend decreased again. The results also showed that the LAR trend decreased from the early vegetative growth period, which can be explained by the faster growth of the daughter corms and other underground parts of the plant than the leaves during the early vegetative growth period. According to the results and the natural trend of mother corm breakup during the growing season, increasing density due to increasing competition between mother corms caused intensification in a weight reduction of mother corms in the late stages of the growing season. Also, in the first three months after sowing, daughter corms did not grow anymore, and the beginning of their growth coincided with the end of the saffron flowering period.

Effect of gypsum and micronutrients on spike and corm yield of gladiolus (Gladiolus grandiflorus ) cv. Guvari

Gladiolus is a nutrient responsive crop that requires major and micro-nutrients viz. N, P, K, Zn, Mn, Fe, B, along with gypsum significantly improves the growth, flowering, yield and quality of corms. In addition, gypsum acts as a source of calcium and soil loosening factor that is needed for corm development. Hence, field experiment was conducted during 2019-2020 at Department of Horticulture, Annamalai University, Tamil Nadu, India on gladiolus cv. Guvari to maximize the yield and quality of spikes and corms. The treatments comprised of ten different combinations of recommended dose of fertilizers (120:150:150 kg/ha NPK), Gypsum (100, 200 and 300 kg/ha) and foliar application of FeSO4, MnSO4 ZnSO4 and HBO(0.5% each in single spray on 30 days 44, 4 33 after planting (DAP) and two sprays on 30 and 45 DAP laid out in Randomized Block Design with three replications. The growth, flowering, and corm yield parameters were periodically assessed. The results revealed that application of gypsum and micronutrients significantly increased the vegetative growth, flowering, spike yield, and corm yield. Application of 300 Kg/ha gypsum was found effective when compared to low doses. Among the ten treatments, application of 120:150:150 kg/ha NPK + 300 kg/ha Gypsum + foliar spray of (0.5% each) FeSO4, MnSO4 ZnSO4 and H3BO3 at 30 and 45 DAP found most 44, 4 33 effective with higher plant height, leaf area, root dry weight, dry matter production, spike length, floret diameter, spike yield, and number of marketable spikes per plant. The corm yield parameters including corm weight, number of daughter corms per plant, number of cormels per plant and weight of daughter corms were also superior in this treatment. Hence, it is confirmed that the application of 300 kg/ha gypsum + foliar spray of (0.5% each) FeSO4, MnSO4ZnSO4 and H3BO3 at 30 and 45 days after planting P along 44, 4 33 with 120:150:150 kg/ha NPK proved maximizing the spike and corm yield of gladiolus.

Effect of crop regulation practices on spike and corm yield of gladiolus (Gladiolus hybrids Hort.) cv Sarala

Standardization of the crop regulation practices is vital for spike and corm yield maximization in gladiolus (Gladiolus hybrids Hort.). Hence, a field experiment was conducted in factorial randomized block design with three replications at Annamalai University, Annamalai Nagar, during 2019 with the objective to maximize the spike and corm yield of gladiolus by growth regulators and leaf regulation practices done after spike harvest. The gladiolus cv. Sarala was tested with 15 treatment combinations comprising growth regulator treatments of corms viz., 100ppm GA3(G1), 150ppm GA3(G2), 100ppm IAA(G3), 150ppm IAA (G4), and Control(G5)and leaf regulation practicesviz.,harvesting spike leaving all leaves (L1), harvesting spike with three leaves (L2), and clipping leaves at 20cm above the base (L3). The results revealed that the growth regulator treatments, given to corms significantly influenced the growth, flowering, and spike yield of gladiolus. Corm soaking treatment of GA3@150 ppm evinced the best treatment in respect of growth, flowering, and spike yield of gladiolus. Though, the effect of leaf regulation practices on growth and flower yield were insignificant, but their influence in corm yield was significant. The interaction of growth regulator soaking of corms with leaf regulation practices significantly influenced the spike and corm yield. The maximum spike (1.01) and corm yield (1.94) were observed with Corm soaking of GA3@150ppm and harvesting of spikes with three leaves. Leaf regulation by clipping of leaves at 20 cm above the base (L3) had negative influence on corm growth when compared to harvesting of spikes leaving all leaves (L1). The maximum corm diameter (3.25cm) and corm weight (25.4g) were observed with 150 ppm GA3 and harvesting spikes with three leaves. The least corm diameter (2.08cm), number of corms per plant (1.22) and corm weight (17.3g) were recorded with control treatment with cutting leaves at 20cm above the base.

NUTRITIONAL STATUS OF CORN PLANTS ESTIMATED THROUGH DIFFERENT VEGETATION INDICES IN THE GROWTH STAGES

Several vegetation indices (VIs) have been proposed in the literature with the objective of exploring the spectral properties of the vegetation as they are usually related to biophysical parameters of the plants. The objective of this study was to evaluate the relationship between VIs, obtained in two different RPAS platforms (Remotely-piloted spacecraft system) and proximity system at different corm growth stages with the nitrogen (N) nutritional status in the plant. Five treatments with different nitrogen fertilizer rates (20, 60, 120, 180 and 240 kg ha-1) were studied in order to generate the variability of nitrogen uptake by the plant in four blocks with five replicates each. Reading of the following VIs were performed: NDRE and NDVI (proximity sensing, Optrix sensor) and NDRE, NDVI, EVI2 and GNDVI (RPAS platform, MicaSense Parrot Sequoia sensor) at the phenological stages V5, V6, V7, V9, V11 and V12. Corn plants were collected to evaluate N content in the aerial part of the plant. The N content was higher in V7 growth stage and lower in V12 stage. The VIs obtained through the RPAS platform presented higher relationship with the corn nutritional status when compared to the proximity sensors. The V12 corn growth stage had higher relationship of VIs and plant N content in comparison to the proximity sensor.

Effect of electric current severity and shock timing of corms on vegetative growth, flowering and corm yield characteristics of two cultivars of gladiolus (Gladiolus grandiflorus) plant

The study was conducted in the Greenhouse of Horticulture Department, College of Agricultural Engineering Sciences, Duhok University, Iraq during spring season of 2019 to investigate the effect of electric current severity and shock timing of corms on the vegetative, flowering and corm growth characters of Gladiolus grandiflorus. The treatments including three levels of electric current severity (AC 6, 8 and 10 amp.) and three timings of electric shock (1, 3 and 5 min) were tested on corms of two cultivars of gladiolus (Bimbo and Sapporo). A special electric apparatus was designed for this purpose. The corms were first soaked for 3 h in 1% NaCl solution, and then soaked in fresh water for the same period of 3 h before planting. The corms of cv. Bimbo which were exposed to low current for a short period treatment (T1) i. e. 4 A × 1 min significantly reduced sprouting time of vegetative growth to 12 days and flowering date to 68 days, increased the number of lateral branches (2.75 lateral branches/plant), largest leaf area (191.35 cm2), chlorophyll content (59.65 SPAD), longest spike flower (12.50 cm), highest number of florets in spike flower (27.85 flowers/spike) and highest dry weight of corms (19.81 g). However, the treatment T15 (6 A × 3 min) significantly increased the plant height (128.95 cm), dry weight of vegetative parts (12.09 g) and diameter of corm (6.13 cm).

Response of saffron (Crocus sativus L.) to irrigation water salinity, irrigation regime and planting method: Physiological growth and gas exchange

Salinity stress reduces the crop water up-take which causes reduction in growth rate and productivity. Split-split plot arrangement was used to analyze the effects of irrigation water salinity (0.45 (well water, S1), 1.0 (S2), 2.0 (S3), 3.0 (S4) dS m−1), irrigation water levels (100% (I1). 75% (I2) and 50% (I3) of saffron water requirement (WR)) and planting methods (basin (P1) and in-furrow (P2) planting) on physiological growth and gas exchange of saffron (Crocus sativus L.) in open field conditions in two growing seasons. Saffron leaf dry matter (LDM) increased 59.6%, on average, in all treatments in the second growing season compared with that obtained in the first growing season due to corm growth in the second year. The main effects of irrigation regime on corm yield reduction was significant only in 50% WR (as19.1%) and in high salinity level (3.0 dS m−1 as 33.3%) in both years. Results indicated that salinity levels of 2.0 and 3.0 dS m−1 decreased the corm density 14.6% and 23.3% in the first growing season. In-furrow planting method significantly increased LDM (57.1%), corm yield (50.4%), leaf area index (LAI) (48.8%), photosynthesis rate (An) (40.3%) and stomatal conductance (gs) (41.2%) in both growing seasons. The intercept of relationship between flower and corm yield and between flower and LDM showed that approximately 5887 kg ha−1 of corms and 380 kg ha−1 of LDM have not participated in flower production as threshold. High irrigation water salinity, 3.0 dS m−1, reduced LAImax 31.9% and 45.7% in the first and second growing season, respectively. Salinity level of 2.0 and 3.0 dS m−1 reduced the crop growth ratio (CGR) significantly in comparison with that obtained in 0.45 dS m−1. Results showed that 50% WR reduced An by 21.8% and 27.2% in comparison with that obtained in 100% WR in the first and second growing seasons, respectively. Also, salinity levels of 2.0 and 3.0 dS m−1 reduced An by 21.5% and 27.2% in comparison with that obtained in 0.45 dS m−1 in the first growing season and 21.4% and 36.6% in the second growing season, respectively. Therefore, the water stress effects of 75% WR and 50% WR were corresponding to salinity stress effects of 2.0 and 3.0 dS m−1 salinity level, respectively. The results showed that inappropriate field management and strategies (i.e. basin planting method) reduced the corm planting density and resulted in negative effects of deficit irrigation and saline water on corm yield, saffron physiological growth and gas exchange phenomena that can be compensated by in-furrow planting method.